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2026-08-19
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ai-policy
Microsoft's 2026 Outlook Deliverability Crackdown: Why Emails Bounce with 550 5.7.15
Microsoft's 2026 enforcement of its high-volume sender requirements, announced April 2, 2025, and enforced since May 5, 2025, now causes hard SMTP rejections with error 550 5.7.15 for domains sending …